The present invention relates to a dragline bucket for large excavating draglines, which is supported by a pair of hoist chains mounted toward the front from the center of gravity of the bucket, so that the bucket dumps over its rear wall under control of drag chains and cables.
Prior art dragline buckets are extremely heavy, rugged buckets that have front teeth for digging and which are supported on a pair of hoist chains located toward the rear of the bucket. The buckets are filled by pulling the bucket with drag chains. The material in the bucket is dumped over the front teeth using a dumping system consisting of dump cable sheave or sheaves, dump rigging cables and attachments. The bucket construction generally requires some type of a spreader bar or high arch at the front of the bucket, and a number of cables, sheaves and dump rigging components for controlling the bucket material during the swing and dumping cycle. Dumping out the front end drops the material in a direction toward the dragline power unit, thereby minimizing the available space in which the overburden material can be piled, because the length of the supporting boom for a dragline is necessarily limited due to load, size and weight considerations.
A lighter weight dragline bucket that utilizes a somewhat lower rear wall than most standard buckets is shown in U.S. Pat. No. 4,944,102. U.S. Pat. No. 4,944,102 has the hoist chains mounted near the rear of the bucket but on the inside. This placement of the hoist chain necessitates having strong or reinforced sidewalls on the bucket and also a cross bar is used on the front end of the bucket for strength purposes. The bucket is dumped out the front and is controlled through the use of dump ropes or cables attached to the drag chains, requiring a set of sheaves and other rigging component parts that increases costs and maintenance. The present invention eliminates many of the problems by lightening the bucket, and reducing the number of component parts needed, which results in a lighter weight, more efficient and lower cost operating bucket and rigging system.